Bone conductive speaker

ABSTRACT

A bone conductive speaker is downsized without causing any loss in efficiency, simple in construction low in cost, and comprises yoke ( 2 ), magnet ( 3 ) disposed in a central area of the yoke, and voice coil ( 4 ) wound on the magnet. The yoke has its peripheral area divided into a plurality of upright portions; of the upright portions, each of first ones ( 5 ) oppositely disposed from each other is provided with a first engaging means ( 9 ) in its upper surface; second engaging means ( 8 ) each corresponding to the first engaging means are provided in a vibrating plate ( 7 ). The vibrating plate is mounted on a lid portion of the housing in a manner such that the vibrating plate is disposed on the upright portions of the yoke and fixedly mounted by means of the second engaging means in a manner such that the vibrating plate floats in the housing.

FIELD OF THE INVENTION

The present invention relates to a bone conductive speaker, and moreparticularly to a bone conductive speaker of a type adapted to be heldin abutting contact with a head portion of a user for transmitting avibration of a diaphragm or vibrating plate of the bone conductivespeaker to a bone tissues of the head portion of the user, which makesit possible for the user to catch the sound.

BACKGROUND OF THE INVENTION

A conventional bone conductive speaker has a known construction such asone shown in FIGS. 4(A) and 4(B). Such bone conductive speaker isconstructed of: a cylindrical casing 21 provided with a diaphragm orvibrating plate 22 in its upper surface; a magnet 23 mounted in thecasing 21 in an insertion manner; a yoke 25, which is mounted in a lowerportion of the casing in an insertion manner and provided with a centermagnet pole 24 in its central area; and, a voice coil 26, with which thecenter magnet pole 24 of the yoke 25 is encircled.

This type of conventional bone conductive speaker has its componentssuch as the center magnet pole 24, the voice coil 26, the magnet 23 andthe casing 21 concentrically arranged radially outwardly in the order ofmention in the above. Due to this, and since both the center magnet pole24 and the voice coil 26 are encircled with both the magnet 23 and thecasing 21, it is necessary to increase both the magnet 23 and the casing21 in diameter in order to increase the center magnet pole 24 indiameter and increase the number of turns for the voice coil 26. Thismakes it inevitably necessary to increase the bone conductive speaker inouter diameter.

In order to improve the bone conductive speaker in output efficiencywithout causing such increase in its outer diameter, a second type ofconventional bone conductive speaker such as one shown in JapanesePatent No. 2967777 has been already proposed, which one is shown inFIGS. 5(A) and 5(B) and has a construction in which: a yoke 31, which isdisposed in a housing 30, and provided with a center magnet pole 32encircled with a voice coil 33; a magnet 34, which is disposed in eachof a pair of diametrically-opposing ones 37 of four extension portions37, 38 of the yoke 31; a pair of upright diaphragm-support portions 36each disposed in each of a pair of the remaining extension portions 38of the yoke 31; and, a diaphragm or vibrating plate 35 fixedly mountedon these diaphragm support portions 36.

This second type of conventional bone conductive speaker is called theouter magnet type, in which the magnets 34 are disposed in an outerperipheral portion of the speaker. In this second type of boneconductive speaker, the magnets 34 and the diaphragm support portions 36(which corresponds to the casing 21 of the first conventional boneconductive speaker) are disposed on the same circle in contrast with thefirst conventional bone conductive speaker in which the magnets 23 andthe casing 21 are concentrically arranged so as to form a doubled-wallstructure. Due to this, the second type of conventional bone conductivespeaker may be reduced in its installation space by half of its ancestoror first type of conventional bone conductive speaker. This makes itpossible for the second type of conventional bone conductive speaker tobe improved in output efficiency by increasing its center magnet pole 32in diameter and increasing the number or turns for its voice coil 33,without causing any increase of its outer diameter.

In recent years, much more downsizing is required of the bone conductivespeaker with the widening of its applications, for example such asincorporation in a cellular phone and like applications. In the outermagnet type of conventional bone conductive speaker, however, since itsmagnet is disposed in the outer peripheral portion of the speaker, andalso since it is difficult to produce the magnet of a slim orthin-thickness type having a sufficient physical strength at a low cost,it is necessary for the outer magnet type of bone conductive speaker toprevent its magnet from being too reduced in size. Due to this, it isnot possible for the conventional bone conductive speaker tosufficiently meet the demand for much more downsizing of the speaker.

Further another type of conventional bone conductive speaker is shown inFIG. 6. This type of conventional bone conductive speaker is called theinner magnet type, wherein: disposed in a central area of a bowl-likeyoke 42 is a magnet 41 which is encircled with a voice coil 43; the yoke42 is received in a housing 44; and, a diaphragm or vibrating plate 45is supported on an upper surface of the housing 44.

In this type of conventional bone conductive speaker, however, it isnecessary for the housing 44 to have a sufficient diameter in order tosupport the vibrating plate 45 in a manner such that the vibrating plate45 is easily vibrated in operation. This is because the vibrating plate45 is supported on the upper surface of the housing 44. Consequently,also in this inner magnet type of bone conductive speaker, it is notpossible to meet the demand for much more downsizing of the speaker.

As described above, any type of the conventional bone conductive speakerfails to meet the demand for much more downsizing of the speaker inincorporating the bone conductive speaker into a cellular phone. Undersuch circumstances, the present invention was made to meet the demand.Consequently, it is an object of the present invention to provide a boneconductive speaker, which is easily produced at a low cost to meet thedemand.

SUMMARY OF THE INVENTION

The above object of the present invention is achieved by providing: abone conductive speaker comprising a yoke (2), a magnet (3) disposed ina central area of the yoke, and a voice coil (4) wound on the magnet(3), wherein: the yoke (2) has its peripheral area divided into aplurality of upright portions; of the upright portions, each of a pairof first ones (5) oppositely disposed from each other is provided with afirst engaging means (9) in its upper surface; a pair of second engagingmeans (8) each corresponding to the first engaging means (9) areprovided in a vibrating plate (7); the vibrating plate (7) is mounted ona lid portion of the housing in a manner such that the vibrating plate(7) is disposed on the upright portions of the yoke and fixedly mountedby means of the second engaging means in a manner such that thevibrating plate floats in the housing.

In the bone conductive speaker having the above construction,preferably: each of the first engaging means provided in the uppersurface of the upright portions is constructed of an engagingprojection; each of the second engaging means provided in the vibratingplate is constructed of a notch portion of the vibrating plate; and, thefirst engaging projection of the yoke is engaged with the notch portionof the vibrating plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of the bone conductive speakerof the present invention, illustrating the entire construction of thespeaker.

FIG. 2 is an exploded perspective view of the bone conductive speaker ofthe present invention, illustrating both a vibrating portion and a driveportion of the speaker.

FIG. 3 is a perspective view of an assembly, wherein the assembly isassembled from both the vibrating portion and the drive portion of thebone conductive speaker of the present invention.

FIGS. 4(A) and 4(B) show a conventional type of bone conductive speakerin construction.

FIGS. 5(A) and 5(B) show another type of conventional bone conductivespeaker.

FIG. 6 shows still another type of conventional bone conductive speaker.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the accompanying drawings, embodiments of the presentinvention will be described. FIG. 1 is a longitudinal sectional view ofthe bone conductive speaker of the present invention, illustrating theentire construction of the speaker comprising a housing 1. FIG. 2 is anexploded perspective view of the bone conductive speaker of the presentinvention, illustrating a vibrating portion and a drive portion of thespeaker both received in the housing 1. FIG. 3 is a perspective view ofan assembly, wherein the assembly is assembled from both the vibratingportion and the drive portion of the bone conductive speaker of thepresent invention.

As shown in FIG. 1, the housing 1 is divided into: an upper portionwhich is formed into a lid portion 1 b; and, a lower portion which isformed into a container portion 1 a in which the drive portion isreceived in a floating manner. The lid portion 1 b of the housing 1 isfixedly mounted on the drive portion thereof.

This drive portion of the housing 1 is constructed of: a bowl-like yoke2; a magnet 3 disposed in a central area of the yoke 2; and, a voicecoil 4, with which the magnet 3 is encircled. The peripheral wallportion of the yoke 2 is divided into a plurality of upright portions(four upright portions in an example shown in the drawings). Of theseupright portions, each of a pair of ones 5, 5 oppositely disposed fromeach other is formed into a diaphragm support for supporting a diaphragmor vibrating plate 7. The remaining ones 6, 6 of the upright portions ofthe yoke 2 thus divided are oppositely disposed from each other tobecome components of a magnetic circuit.

Provided in an upper surface of each of the upright portions 5, 5 forreceiving the vibrating plate 7 is a first engaging projection 9. Thisengaging projection 9 is engaged with each of second engaging means suchas notch portions 8, 8 in an insertion manner, wherein the notchportions 8, 8 are formed in opposite end portions of the vibrating plate7. Due to the above construction, it is possible for the vibrating plate7 to have its notch portions 8, 8 engaged with the first engagingprojections 9, 9 of the yoke 2 in an insertion manner from upside asviewed in FIG. 2. This makes it possible to fixedly mount and positionthe vibrating plate 7 on the yoke 2, without requiring any additionalspace for welded or adhered portions of the vibrating plate 7.Consequently, the bone conductive speaker of the present invention iscapable of being sufficiently downsized.

The vibrating plate 7 assumes a circular shape provided with fourengaging projections and four concave portions. Of these four engagingprojections, each of a pair of engaging projections oppositely disposedfrom each other is provided with the notch portion 8 in its free endportion On the other hand, a large-sized rectangular central opening 10is formed in a central area of the vibrating plate 7.

The reference numeral 11 denotes a plate yoke. The plate yoke 11 extendsalong the central opening 10 of the vibrating plate 7, and has itsopposite end portions mounted on the remaining ones of theabove-mentioned four engaging projections of the vibrating plate 7,which remaining ones are not provided with any notch portion. Theseopposite end portions of the plate yoke 11 are fixedly mounted on theremaining ones of the engaging projections of the vibrating plate 7through a welding process, an adhering process or like fastening means.Due to this, the drive portion and the vibrating portion of the boneconduction speaker are assembled into an assembly, wherein: the driveportion of the speaker comprises the yoke 2, magnet 3 and the voice coil4; and, the vibrating portion of the speaker comprises the vibratingplate 7 and the plate yoke 11 (see FIG. 3).

In general, a pair of threaded holes 12, 12 are formed in the plate yoke11. Each of The threaded holes 12, 12 of the plate yoke 11 is threadablyengaged with each of set screws 13, 13 which have passed through thecorresponding through-holes of a lid portion 1 b of the housing 1. As aresult, the assembly assembled from both the vibrating portion and thedrive portion of the speaker is incorporated in the housing 1 in amanner such that the assembly is suspended from the lid portion 1 b soas to float above the inner bottom surface of the container portion 1 aof the housing 1 (see FIG. 1). Incidentally, although not shown in thedrawings, a suitable signal input line is arranged in the housing 1.

In the bone conductive speaker of the present invention having the aboveconstruction, when the drive portion of the speaker receives a sound oraudio input signal, the vibrating portion of the bone conduction speakerbegins to vibrate. Such vibration of the vibrating portion of thespeaker is effectively transmitted to the housing 1. This makes itpossible to realize a bone conductive speaker excellent in outputefficiency.

The above-mentioned embodiment of the present invention is a simple oneof various examples. Due to this, it is natural that the presentinvention is not limited to this example. For example, it is alsopossible for the present invention to provide an appropriate lighteninghole in the vibrating plate 7 in order to reduce the vibrating plate inweight. Further, it is also possible for the present invention tofixedly mount the plate yoke 11 on the lid portion 1 b of the housing 1by means of a single set screw 13. Still further, it is also possiblefor the present invention to modify each of the notch portions 8 and theengaging projections 9 into any desired shape.

In place of the provisions of both the notch portion 8 and the engagingprojection 9, it is also possible to employ a convex portion formed in arear surface of the vibrating plate 7 together with a concave portionformed in the upper surface of each of the upright portions 5, 5 of theyoke 2, which concave portion corresponds in position to the convexportion of the vibrating plate 7 and is fixedly engaged with the convexportion of the vibrating plate 7 in an insertion manner.

INDUSTRIAL APPLICABILITY

The present invention has a construction as described above. In the boneconductive speaker of the present invention: both the upper surfaces ofthe peripheral upright portions of the yoke and the vibrating plate ofthe speaker are provided with their engaging means, through which meansthe vibrating plate is fixedly mounted on the upright portions of theyoke. Further, in the bone conductive speaker of the present invention,since the magnet is disposed in the central area of the yoke, it ispossible to reduce the upright portions of the yoke in thickness. Thismakes it possible to reduce the bone conductive speaker of the presentinvention in diameter as a whole, which makes it possible tosufficiently meet the demand for incorporating the bone conductivespeaker of the present invention into a cellular phone or like units.Further, in the bone conductive speaker of the present invention, it isalso possible to increase the number of turns for the voice coil withoutany loss of output efficiency. Still further, it is also possible torealize the bone conductive speaker of the present invention at a lowcost in an easy manner. These are advantages and effects inherent in thepresent invention.

1. A bone conductive speaker comprising a yoke (2), a magnet (3)disposed in a central area of said yoke, and a voice coil (4) wound onsaid magnet (3), wherein: said yoke (2) has its peripheral area dividedinto a plurality of upright portions; of said upright portions, each ofa pair of first ones (5) oppositely disposed from each other is providedwith a first engaging means (9) in its upper surface; a pair of secondengaging means (8) each corresponding to said first engaging means (9)are provided in a vibrating plate (7); said vibrating plate (7) ismounted on a lid portion (1 b) of a housing (1) in a manner such thatsaid vibrating plate (7) is disposed on said upright portions of saidyoke (2) and fixedly mounted by means of said second engaging means in amanner such that said vibrating plate (7) floats in said housing (1). 2.The bone conductive speaker as set forth in claim 1, wherein: each ofsaid first engaging means provided in said upper surface of said uprightportions is constructed of an engaging projection (9); each of saidsecond engaging means provided in said vibrating plate is constructed ofa notch portion (8) of said vibrating plate; and, said first engagingprojection of said yoke is engaged with said notch portion of saidvibrating plate.
 3. The bone conductive speaker as set forth in claim 1,wherein: said first engaging means provided in said upper surface ofsaid upright portion of said yoke is constructed of a concave portion ora convex portion; and, said second engaging means provided in saidvibrating plate is constructed of a convex portion or a concave portion,which convex portion and said concave portion of said vibrating platecorrespond to said convex portion and said concave portion of said firstengaging means of said yoke, respectively.
 4. The bone conductivespeaker as set forth in claim 1, wherein: said yoke assumes a circularshape; and, each of said upright portions of said yoke assumes acircularly-curved shape in cross section.
 5. The bone conductive speakeras set forth in claim 1, wherein: said vibrating plate is provided witha central opening; and, a plate yoke is fixedly mounted on saidvibrating plate in a manner such that said plate yoke straddles saidcentral opening of said vibrating plate.
 6. The bone conductive speakeras set forth in any one of claims 1 to 5, wherein said vibrating plateis provided with a lightening hole portion in order to reduce itsweight.